The present invention relates to semiconductor-supporting devices, processes for producing the same, joined bodies and processes for the production of the same.
In susceptors and the like made of ceramic materials such as aluminum nitrides, alumina, SiC or SN, materials for electrode terminals are selected from the standpoint of the heat resistance, corrosion resistance, and bondability, but there are very rare materials which completely meet the above requirements. For example, in a method of brazing a metallic terminal to a ceramic substrate, troubles such as cracking of the ceramic material due to residual stress at the time of joining or thermal stress of current-passing cycles in switching on and off the electric power are likely to occur.
For this reason, it is considered that the terminal is imparted with a plastically deforming power by using a metal having a low melting point or a high purity metal as a material of the terminal. However, since the terminal itself has a poor shape-maintaining property, a problem such as the deformation of the terminal rises, or the joining interface becomes brittle due to an excess reaction between the terminal and the brazing material, so that the joining strength sometimes drops.
On the other hand, it is known that a metal-based composite material is produced by a Lanxide process (for example, see Ceramics xe2x80x9cCMC and MMC Net Shave Producing Technique by using Rank Side Systemxe2x80x9d Vol. 32(1997) No. 2, pp 93-97). For example, it is known that wettability between molten aluminum and ceramics is improved by the rank side process in each of a silicon nitride/aluminum-based composite material and an aluminum/aluminum-based composite material. This process is generally called xe2x80x9cnon-pressure metal immersion processxe2x80x9d.
In this process, a preform having a shape near to a desired final shape is molded by using silicon carbide or alumina as a reinforcing material, and a growth-interrupting barrier film is formed at a surface of the preform other than that of the preform to which an aluminum alloy is contacted. When the resulting preform is contacted with the aluminum alloy usually at around 800xc2x0 C. in nitrogen, the aluminum enters voids in the preform while wetting the ceramic material, thereby forming a composite material. In this composite material, it is confirmed that a layer of aluminum nitride is present at an interface between the ceramic material and the aluminum.
However, a technique in which such a metallic matrix-ceramic composite body is joined to a ceramic material or a metal, particularly to an insulating ceramic has not been investigated.
The present invention is directed to a semiconductor-supporting device which comprises a substrate composed of an insulating material, an electrically conductive member buried in the substrate, and a terminal connected to the electrically conductive member, and is to improve the durability at a joint portion between the insulating material and the terminal against current-passing cycles.
Further, the present invention is to provide a process for joining a metallic matrix-ceramic composite body to a ceramic material, a metal or a ceramic material in which a metal is buried.
The present invention is further to provide a new process for joining plural members made of a ceramic material and a metal or a ceramic material in which a metal is buried.
The present invention relates to a semiconductor-supporting device comprising a substrate made of an insulating material, a conductive member buried in the substrate, and a terminal connected to the conductive member and made of an electrically conductive metallic matrix-ceramic composite body.
The present inventors thought that the terminal be formed of the metallic matrix-ceramic composite body having conductivity in the structure in which the terminal was joined to the substrate made of the insulating ceramic material. It was discovered that while the terminal was directly contacted with the substrate or while an intermediate material composed of an alloy containing 70 mol % or more of a main ingredient of the metallic matrix constituting the metallic matrix-ceramic composite body is interposed between the terminal and the substrate, the terminal could be joined to the insulating material by thermally treating the insulating material and the terminal or by thermally treating the insulating material, the terminal and the intermediate member at a temperature enabling a metallic matrix constituting the metallic matrix-ceramic composite body or the metallic matrix and the alloy to be melted, in an atmosphere under pressure of 0.0001 Torr or less. Since this terminal was firmly joined to the substrate, the joined portion was not broken even under repetition of current-passing cycles.
The present invention further relates to a semiconductor-supporting device comprising a substrate made of an insulating material, a conductive member buried in the substrate, a terminal connected to the conductive member and made of a metal or a conductive ceramic material, and a joining member interposed between the terminal and the substrate, joined to the terminal and the substrate and made of a metallic matrix-ceramic composite body.
In such a semiconductor-supporting device, since this terminal is firmly joined to the substrate, the semiconductor-supporting device is not broken even under repetition of current-passing cycles.
Further, the present inventors reached a technical idea that when the above invention was applied to join one member made of a metallic matrix-ceramic composite body other than the terminal to another member made of a ceramic material, a metallic material or a ceramic material in which a metallic member was buried. As a result, it was discovered that the composite body could be joined to said another member by thermally heating both the metallic matrix-ceramic composite body and another member at a temperature enabling the melting of the metallic matrix constituting the metallic matrix-ceramic composite body in an atmosphere under pressure of 0.0001 Torr or less.
In this case, the thermal treatment can be effected, while the metallic matrix-ceramic composite body is in direct contact with another member. Alternatively, an intermediate material composed of an alloy containing 70 mol % or more of a main ingredient of the metallic matrix constituting the metallic matrix-ceramic composite body may be interposed between them in the thermal treatment.
The present invention relates to the joined body obtained by each of the above producing processes, which comprises one member made of the metallic matrix-ceramic composite body and another member made of the ceramic member, the metallic member or the ceramic member in which the ceramic member is buried.
The present inventors further developed the above-mentioned joining processes, and discovered that while a joining member made of a metallic matrix-ceramic composite body is interposed between one member made of a ceramic member, a metallic member or a ceramic member in which a ceramic member is buried and another member made of a ceramic member, a metallic member or a ceramic member in which a ceramic member is buried, one and another members can be joined together by thermally treating them as well as the joining member at a temperature enabling the melting of the metallic matrix constituting the metallic matrix-ceramic composite body in an atmosphere under pressure of 0.0001 Torr or less.
In this case, the thermal treatment can be effected, while the metallic matrix-ceramic composite body is in direct contact with one and another members. Alternatively, an intermediate material composed of an alloy containing 70 mol % or more of a main ingredient of the metallic matrix constituting the metallic matrix-ceramic composite body may be interposed between the one member and the joining member and/or between another member and the joining member in the thermal treatment.
The present invention further relates to the joined articles obtained by the above processes.
These and other objects, features and advantages of the invention will be appreciated upon reading the following description of the invention when taken in conjunction with the attached drawings, with the understanding that some modifications, variations and changes could be easily made by the skilled person in the art to which the invention pertains.